Display devices are used for various apparatuses, such as smartphones, tablet terminals, mobile phone terminals, personal computers, television receivers, in-vehicle devices, game consoles, and wearable terminals.
Generally, transmission-type display devices, such as liquid crystal display devices, include a backlight including a light source unit and a light guide plate, a display panel, and polarizers arranged on both sides of the display panel. In the backlight, light from the light source is made incident on the light guide plate, and applied to the display panel from an emitting surface of the light guide plate.
The light guide plate is formed of a resin material. The light guide plate formed of such a material absorbs part of light from the light source, and may cause reduction in luminance of the emitting surface and non-uniformity in luminance in the emitting surface. In addition, the material of the light guide plate may be deformed due to heat, load, and moisture, and non-uniformity in luminance may occur also in this case. Besides, absorption of light in the light guide plate has wavelength dependence, and the wavelength dependence may cause color shift in which the light emitted from the emitting surface is shifted from the originally intended color, and color non-uniformity in the emitting surface.